The Steyr AUG is a selective-fire, bullpup weapon with a conventional gas-piston-operated action that fires from a closed bolt. It is designed as a Modular Weapon System that could be quickly configured as a rifle, a carbine, a sniper rifle, a sub-machine gun and even an open-bolt squad automatic weapon. The AUG employs a very high level of advanced firearms technology and is made with the extensive use of polymers and aluminium components. It is chambered in 5.56�45mm NATO cartridge and has the 1:7 rifling twist that will stabilise both SS109/M855 and M193 rounds.